Electrodynamic loudspeaker and mounting therefor



p 1950 s. s. CARBONNEAU 2,522,859

ELECTRODYNAMIC LOUDSPEAKER AND MOUNTING THEREFOR Filed Jan. 30, 1948 INVEN TOR. 60/0 00 6. 60/50/7020 Patented Sept. 19, 1950 UNITED STATESPATENT OFFICE Gordon S. Carbonneau, Grand Rapids, Mich.

Application January 30, 1948, Serial No. 5,329

14 Claims. (Cl. 179115.5)

This invention relates to improvements in radio loud speakers.

The principal objects of this invention are:

First, to provide a housing and magnetic structure for a loud speakerwhich will require less steel than conventional structures and at thesame time improve the magnetic and acoustic characteristics of thespeaker.

Second, to provide a radio loud speaker which is more rigid thanconventional speakers thus eliminating to a large degree undesirablevibrations in the frame structure.

Third, to provide a mounting for the cone of a loud speaker with areduced amount of material overlying the rear of the cone thuseliminating a large amount of the interference and sound pressure peakscaused by the reflection of sound waves from the frame structure to therear of the cone.

Fourth, to provide a mounting for the cone of a loud speaker having anaccurately controllable effective clamp ring diameter and providing amaximum accessibility to the several elements of the speaker to permiteasy installation and inspection of the elements.

Fifth, to provide a mounting for the cone of a loud speaker whicheifectively protects the front and back of the cone where the cone ismost liable to be damaged during mounting in a radio set and which maybe easily clamped to a support without danger of distorting the frameand thus causing undesirable strains in the speaker cone.

Sixth, to provide a loud speaker structure which will have a maximumdegree of magnetic efiiciency with a minimum amount of steel due to thelocation of more metal along the point of greatest magnetic reluctanceand reducing the amount of metal where it will cause magnetic leakagefrom the speaker magnet.

Other objects and advantages pertaining to the details and economies ofmy invention will be apparent from a consideration of the followingdescription and claims. The drawings, of which there is onesheet,illustrate a preferred form of my loud speaker.

Fig. 1 is a side elevational view of my speaker mounted on a suitablesupport and partially broken away in vertical cross section along theline l--! in Fig. 2 to illustrate details of construction thereof.

Fig. 2 is a rear elevational view of my speaker partially broken away invertical cross section along the line 2-2 in Fig. 3.

Fig. 3 is a longitudinal cross sectional view through the magnet of myspeaker taken along the line 3-3 in Figs. 1 and 2.

leaving a recess 10.

Fig. 4 is a fragmenetary perspective view of the foot for attaching myspeaker to the support.

The supporting structure for my speaker which takes the place ofconventional basket structures consists of an annular ring I ofrelatively heavy gage metal having a forwardly opening cylindric flange'2 and a flat back flange 3 defining the clamp ring opening 4. The ringI is secured to a single strap 5 of relatively heavy gage steel having acentral base 6 from which the arm portions 1 diverge toward the edges ofthe ring. The outer ends of the arms I are bent forwardly and areslightly concave as at 8 to fit closely along the outside of thecylindric flange 2 of the ring. The forwardly bent portions 8 have thefeet 9 stamped and folded upwardly therefrom thus The feet 9 define theslots H (see Fig. 4) for receiving the mounting bolts I2 for clampingthe speaker to a support panel 13.

The magnet structure of my speaker is secured to the base 6 of the strapand consists of a loop magnet l4 formed of a strip of heavy gage steelfolded into rectangular shape with its ends forming an air gap l5opposite the center of the base 6 of the strap. The magnet loop is is,preferably formed with small projections on its forward face andpressure welded to the base of the strap as at l6. It will be noted fromFigs. 1 and 2 that the base 6 of the strap thus forms an. integral andsubstantial bridge for the .air gap of the magnet loop I4 materiallyreducing the magnetic reluctance of the air gap so that I am able toform the loop 14 of substantially lighter gage material than is requiredin other magnets to obtain comparable operating results.

After the loop M has been welded to the base of the strap the coilaperture I i can be accurately reamed through both the strap and themagnet and centered along. the air gap l5. The remaining elements of myspeaker are of more or less a conventional design including the polepiece [8 having a reduced forward end l9 projecting into the coilopening anda mounting ring 20 engaged with a shoulder on the pole piece.The voice coil 2| is wound on paper tube 22 and a sealing diaphragm 23is cemented to the forward face of the base of the strap and to thecircumference of the tube.

My cone 24 is of conventional paper or fiber construction having anannular mounting flange 25 around the forward edge thereof which iscemented to the inturned flange 3 of the clamp ring. The rear end of thecone 24 is provided with a cylindrical flange 26 cemented to the forwardend of the voice coil .tube and a dust shield 21 is provided at theinner end of the speaker cone to prevent the entrance of dust into thespeaker coil tube.

One arm of the strap defines a rectangular aperture 3i! bridged by aninsulating terminal stri 35 on which are mounted the terminals 32. Lead.wires 33 connect the terminals 32 to the voice coil 2|.

Particular attention is called to Figs. 1 and i in which it will benoted that the cylindric flange 2 of the clamp ring is welded to theforwardly bent portions of the strap as at 28 with the for ward edge ofthe flange 2 spaced slightly inwardly from the feet 9 on the strap. Thuswhen the feet are clamped to the supporting panel by the bolts E2 theforward edge of the clamp ring will be spaced slightly from the rearsurface of the panel 53 as at It is thus impossible for an inexperiencedor careless workman to clamp the speaker to the panel 53 in such afashion as to distort or twist the clamp ring i. If desired, rubberbumpers 34 may be positioned between the free edges of the clamp ringand the supporting panel. l3 to dampen any possible vibration of thespeaker but in most cases this is unnecessary. The base of the feet 9 iscut away as at 35 so that in any case where the feet are not exactlyparallel to the supporting panel is the feet can twist at their relievedportion without distorting the clamp ring.

s It should further be noted that the clamp ring opening 4 is entirelyunobstructed and has an accurately controllable sharp forward edge sothat when the attaching flange 25 of the speaker cone is cementedthereto it is impossible for any portion of the speaker cone to becemented to the clamp ring inside of the clamp ring diameter. Theconnection to the suspended portion of the speaker cone is thusaccurately circular and. the cone is entirely free to vibrate under theinfluence of the voice coil without distortion.

It will be noted from Fig. 2 that the rear sur face of the speaker coneis largely unobstructed so that there is little chance for thereflection of sound waves from the strap to the rear of the cone tocause interference and sound pressure peaks in the response curve of thespeaker cone. It will further be noted that due to the absence of anymetal along thesides of the loop magnet i ithere is little tendency forthe magnet flux to stray from the path of least resistance through themagnet and the base 6 of the strap. This further increases theefficiency of my magnet and speaker assembly as a whole.

In addition to the operating advantages and structural economies of myloudspeaker, the con struction of my speaker mount is particularlyadvantageous in preventing or reducing the amount of accidental damageto speaker cones incident to manufacture and installation of theloudspeakers in radio sets. Most cone damage has been inflicted in thepast from the front of the speaker, either due to mounting screws whichproject from the baffle puncturing the cone, or from laying the conedown on some pro jecting object on a bench.

My mount protects the cone from these hazards in the following manners:

First, the cylindrical flange 2 is deeper than in speakers previouslydevised and the forwardly displaced mounting feet 9 coupled with theflange serve to protect the cone from accidental contact with projectingobjects;

Second, the mounting holes H are spaced laterally from the ring so thereis less likelihood of a workman accidentally placing the cone overHaving thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

l. A radio loud speaker comprising an annular clamp ring having acylindrical forward fiange and a flat rear flange defining a circularclamp ring opening, a strap having a base parallel to said clamp ringwith arms diverging from each end thereof, one of said arms defining anaperture, forwardly bent portions on the ends of said arms welded to theoutside of said cylindrical flange and projecting forwardly thereof,said forwardly bent portions being concave to fit ring, attaching feetstamped from said forwardly bent portions of said arms and bent radiallyout-- wardly of said ring, a loop magnet of rectangularly folded strapmetal welded to said base of said strap with the ends of said magnetpositioned in the middle of said base, said magnet and base defining acoil opening centered with respect to the ends of said magnet and saidstrap, a speaker cone having an annular attaching flange around theouter edge thereof cemented to said rear flange of said clamp ring, anelectromagnetic structure for actuating said cone associated with saidmagnet and the rear end of said cone, an insulating terminal stripbridging said aperture, and voice coil leads for said electro-magneticstructure secured to said terminal strip and extending through saidaperture.

2. A radio loud speaker comprising an annular clamp ring having acylindrical forward flange and a flat rear flange defining a circularclamp ring opening, a strap having a base parallel to said clamp ringwith arms diverging from each end thereof, one of said arms defining anaperture, forwardl bent portions on the ends of said arms welded to theoutside of said cylindrical flange and projecting forwardly thereof,attaching feet stamped from said forwardly bent portions of said armsand bent radially outwardly of said ring, a loop magnet of rectangularlyfolded strap metal welded to said base of said strap with the ends ofsaid magnet positioned in the middle of said base, said magnet and basedefinin a coil opening centered with respect to the ends of said magnetand said strap, a speaker cone having an annular attaching flange aroundthe outer edge thereof cemented to said rear flange of said clamp ring,an electro-magnetic structure for actuating said 'cone associated withsaid magnet and the rear end of said cone, an insulating terminal stripbridging said aperture, and voice coil leads for said electromagneticstructure secured to said terminal strip.

3. A radio loud speaker comprising an annu lar clamp ring having acylindrical forward flange and a flat rear flange defining a circularclamp rin opening, a strap having a base parallel to said clamp ringwith arms diverging from each end thereof, forwardly bent portions onthe ends of said arms welded to the outside of said cylindrical flangeand projecting forwardly thereof, attaching feet stamped from said for'wardly bent portions of said arms and :bent radially outwardly of saidring, a loop magnet of rectangularly folded strap metal welded to saidbase of said strap with the ends of said magnet positioned in the middleof said base, said magnet and base defining a coil opening centered withrespect to the ends of said magnet and said strap, a speaker cone havingan annular attaching flange around the outer edge thereof cemented tosaid rear flange of said clamp ring, and electro-magnetic structure foractuating said cone associated with said magnet and the rear end of saidcone.

4. A radio loud speaker comprising an annular clamp ring having acylindrical forward flange and a flat rear flange defining a circularclamp ring opening, .a .strap having a base parallel to said clamp ringwith arms diverging from each end thereof, forwardly bent portions onthe ends of said arms welded to the outside of said cylindrical flange,attaching feet stamped from said forwardly bent portions of said armsand bent radially outwardly of said ring, a loop magnet of rectangularlyfolded strap metal welded to said base of said strap with the ends ofsaid magnet positioned against said base, said magnet and base defininga coil opening, a speaker cone having an annular attaching flange aroundthe outer edge thereof cemented to said rear flange of said clamp ring,and electro-magnetic structure for actuating said cone associated withsaid magnet and the rear end of said cone.

5. A radio loud speaker comprising an annular clamp ring having acylindrical forward flange and a flat rear flange defining a circularclamp ring opening, a strap having a base parallel to said clamp ringwith arms diverging from each end thereof, forwardly bent portions onthe ends of said arms welded to the outside of said cylindrical flange,attaching feet on said forwardly bent portions of said arms and bentradially outwardly of said ring and lying in a plane forwardly of saidring, a loop magnet of rectangularly folded strap metal welded to saidbase of said strap with the ends of said magnet positioned against saidbase, said magnet and base defining a coil opening, a speaker conehaving an annular attaching flange around the outer edge thereof securedto said rear flange of said clamp ring, and structure for actuating saidcone associated with said magnet and the rear end of said cone.

6. Supporting structure for a radio loud speaker cone comprising anannular clamp ring having a cylindrical forward flange and a fiat rearflange defining a circular clamp ring opening, a single strap memberhaving a base parallel to said clamp ring with arms diverging forwardlyfrom the ends thereof, forwardly bent portions on the ends of said armslapped upon the outside of said cylindrical flange and welded thereto,said forwardly bent portions being slightly concave to match thecurvature of said ring, attaching feet stamped from said forwardly bentportions of said strap and turned radially outwardly from said ring,said feet defining bolt receiving slots and lying in a plane spacedforwardly of the end of said cylindrical flange, and a loop magnethaving an air gap therein and welded to the base of said strap with saidair gap positioned against the center of said base to be bridgedthereby, said base and loop magnet defining a voice coil aperturecentered on said air gap.

7. Supporting structure for a radio loud speaker cone comprising anannular clamp ring having a cylindrical forward flange and a flat rearflange defining a circular clamp ring opening, a single strap memberhaving a baseparallel to said clamp ring with arms diverging forwardlyfrom the ends thereof, forwardly bent portions on the ends of said armslapped upon the outside of said cylindrical flange and welded thereto,said forwardly bent portions being slightly concave to match thecurvature of said ring, attaching feet stamped from said forwardly bentportions of said strap and turned radially outwardly from said ring,said feet defining bolt receiving apertures, and a loop magnet having anair gap therein and welded to the base of said strap with said air gappositioned against said base to be bridged thereby, said base and loopmagnet defining a voice coil aperture centered on said air gap.

8. Supporting structure for a radio loud speaker cone comprising anannular clamp ring having a cylindrical flange and a flat flangedefining a circular clamp ring opening, a single strap member having abase parallel to said clamp ring with arms diverging forwardly from theends thereof, forwardly bent portions on the ends of said arms lappedupon the outside of said cylindrical flange and welded thereto,attaching feet on said forwardly bent portions of said strap and turnedradially outwardly from said ring, said feet defining bolt receivingapertures and lying in a plane spaced forwardly of the end of saidcylindrical flange, and a loop magnet having an air gap therein andwelded to the base of said strap with said air gap positioned againstsaid base to be bridged thereby, said base and loop magnet defining avoice coil aperture.

9. In a radio loud speaker, a loop magnet of rectangularly folded strapmetal having an air gap across the forward side thereof, a strap metalbridge for said air gap welded to the forward side of said magnet andsubstantially co-extensive therewith, said bridge and magnet defining avoice coil opening centered on said air gap, forwardly diverging armsextending from the ends of said bridge, forwardly bent portions on theouter ends of said arms, outwardly bent attaching feet on the ends ofsaid forwardly bent portions and defining apertures for receivingmounting bolts, and a clamp ring having a cylindrical flange Welded tosaid forwardly bent portions on said arms, said clamp ring having a flatflange within said arms defining a circular clamp ring opening.

10. In a radio loud speaker, a loop magnet of rectangularly folded metalhaving an air gap across the forward side thereof, a metal bridge forsaid air gap welded to the forward side of said magnet and substantiallyas wide as said magnet, said bridge and magnet defining a voice coilopening, forwardly diverging arms extending from the ends of saidbridge, forwardly bent portions on the outer ends of said arms,outwardly bent attaching feet on the ends of said forwardly bentportionsand defining apertures for receiving mounting bolts, and a clamp ringhaving a cylindrical flange welded to said forwardly bent portionsonsaid arms, said clamp ring having a flat flange within said armsdefining a clamp ring opening.

11. In a radio loud speaker, a loop magnet of rectangularly folded metalhaving an air gap across the forward side thereof, a metal bridge forsaid air gap Weldedto the forward side of said magnet and substantiallyas wide as said magnet, said bridge and magnet defining a voice coilopening, forwardly diverging arms extending from the ends of saidbridge, outwardly bent attaching feet on the ends of said arms anddefining apertures for receiving mounting bolts, and a clamp ring havinga flange welded to said arms, said clamp ring having a flat flangewithin said arms defining a clamp ring opening.

12. In a radio loud speaker a loop magnet of rectangularl folded metalhaving an air gap across one side thereof, a metal bridge for said airgap welded to said magnet, forwardly diverg ing arms extending from theends of said bridge, outwardly bent attaching feet on the ends of saidarms and defining apertures for receiving mounting bolts, and a clampring having a flange welded to said arms, said clamp ring having a fiatflange within said arms defining a clamp ring opening.

13. Means for mounting the loop magnet of a radio loud speaker on'theclamp ring of the speaker comprising, a strap of steel having a baseportion with forwardly diverging arms on the ends thereof, forwardlybent generally parallel portions on the outer ends of said arms adaptedto be welded to the outside of said clamp ring,

and outwardly turned attaching feet struck from said forwardly bentportions on the forward ends thereof, said base being adapted to bewelded to a side of said magnet, said base being approxi-- mately thesame dimension as the side of the magnet.

14. Means for mounting the loop magnet of a radio loud speaker on theclamp ring of the speaker comprising, a strap of steel having a baseportion with forwardly diverging arms on the ends thereof, said armshaving forwardly folded portions on the ends thereof adapted to bewelded to said clamp ring and having outwardly turned attaching feet onthe forward ends of said forwardly folded portions, said base beingapproximately the same dimension as the side of the magnet.

' GORDON S. CARBONNEAU.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,805,459 Batcher May 12, 19312,016,453 Olney Oct. 8, 1935 2,027,473 C'reager et al Jan. 14, 19362,141,949 Carbonneau Dec. 27, 1938 2,174,355 Sundstrom Sept. 25, 19392,178,030 Bowley Oct. 31, 1939 FOREIGN PATENTS Number Country Date407,474 Great Britain Mar. 22, 1934

